Pearson Daniel A, Bradley R Mark, Motta Francis C, Shipman Patrick D
Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA.
Department of Mathematics, Duke University, Durham, North Carolina 27708, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2015 Dec;92(6):062401. doi: 10.1103/PhysRevE.92.062401. Epub 2015 Dec 1.
When the surface of a nominally flat binary material is bombarded with a broad, normally incident ion beam, disordered hexagonal arrays of nanodots can form. Shipman and Bradley have derived equations of motion that govern the coupled dynamics of the height and composition of such a surface [Shipman and Bradley, Phys. Rev. B 84, 085420 (2011)]. We investigate the influence of initial conditions on the hexagonal order yielded by integration of those equations of motion. The initial conditions studied are hexagonal and sinusoidal templates, straight scratches, and nominally flat surfaces. Our simulations indicate that both kinds of templates lead to marked improvements in the hexagonal order if the initial wavelength is approximately equal to or double the linearly selected wavelength. Scratches enhance the hexagonal order in their vicinity if their width is close to or less than the linearly selected wavelength. Our results suggest that prepatterning a binary material can dramatically increase the hexagonal order achieved at large ion fluences.
当用一束宽的、垂直入射的离子束轰击名义上平整的二元材料表面时，会形成无序的六边形纳米点阵列。希普曼和布拉德利推导了控制这种表面高度和成分耦合动力学的运动方程[希普曼和布拉德利，《物理评论B》84，085420(2011)]。我们通过对这些运动方程进行积分来研究初始条件对产生的六边形有序性的影响。所研究的初始条件是六边形和正弦模板、直线划痕以及名义上平整的表面。我们的模拟表明，如果初始波长大约等于或两倍于线性选择波长，那么这两种模板都会显著改善六边形有序性。如果划痕宽度接近或小于线性选择波长，划痕会增强其附近的六边形有序性。我们的结果表明，对二元材料进行预图案化可以显著提高在大离子通量下实现的六边形有序性。
